@altano/html-cdnify/dist/HtmlAttributeStreamTransformer.js

Transform the relative URLs in your HTML markup (e.g. scripts, stylesheets, images) to use your CDN URL.

import HtmlTransformer from "./HtmlTransformer.js";
import { groupBy } from "lodash";

//#region src/HtmlAttributeStreamTransformer.ts
/**
* Wraps a node-trumpet Transform stream, w/ HTML as input and
* HTML as output. The output will have all non-absolute-URL
* attributes that identify CDN-able resources converted to
* use the given CDN URL.
*/
var HtmlAttributeStreamTransformer = class HtmlAttributeStreamTransformer extends HtmlTransformer {
	condensedTransformOptions = [];
	constructor(options) {
		super();
		this.options = options;
		this.processTransforms();
		this.applyTransforms();
	}
	static attributeParsers = { default: (attr, transformFunction) => transformFunction(attr) };
	applyTransforms() {
		this.condensedTransformOptions.forEach((settings) => {
			const selector = settings.selector;
			const attribute = settings.attribute;
			const parser = settings.attributeParser;
			this.stream.selectAll(selector, (elem) => {
				const oldAttributeValue = elem.getAttribute(attribute);
				if (typeof oldAttributeValue === "string") {
					const newAttributeValue = parser && parser(oldAttributeValue, this.options.transformFunction);
					if (newAttributeValue && newAttributeValue !== oldAttributeValue) elem.setAttribute(attribute, newAttributeValue);
				}
			});
		});
		const { attributeToMarkElementToBeIgnored } = this.options;
		if (attributeToMarkElementToBeIgnored) this.stream.selectAll(`[${attributeToMarkElementToBeIgnored}]`, (elem) => {
			elem.removeAttribute(attributeToMarkElementToBeIgnored);
		});
	}
	processTransforms() {
		this.options.transformDefinitions.forEach((option) => {
			if (!option.attributeParser) option.attributeParser = HtmlAttributeStreamTransformer.attributeParsers["default"];
			if (typeof option.selector !== "string") throw new Error(`Invalid selector specified.`);
			if (typeof option.attribute !== "string") throw new Error(`Invalid attribute specified.`);
			if (!(option.attributeParser instanceof Function)) throw new Error("Invalid attributeParser specified.");
		});
		/**
		* As a performance enhancement, we can condense the list of transformDefinitions such that
		* selectors with the same attribute and attributeParser can be combined into a single,
		* comma-delimited CSS selector.
		*/
		const groupedTransformOptions = groupBy(this.options.transformDefinitions, (obj) => {
			return [obj.attribute, obj.attributeParser];
		});
		this.condensedTransformOptions = Object.values(groupedTransformOptions).map((likeTransformOptions) => {
			const attribute = likeTransformOptions[0].attribute;
			const attributeParser = likeTransformOptions[0].attributeParser;
			return {
				attribute,
				attributeParser,
				selector: likeTransformOptions.map((likeTransformOption) => likeTransformOption.selector).join(", ")
			};
		});
	}
};

//#endregion
export { HtmlAttributeStreamTransformer };
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